Long-chain fatty acid esters of 3α-hydroxy-lup-20(29)-ene-23,28-dioic acid and other triterpenoid constituents from the bark of Schefflera octophylla

From the bark of Schefflera octophylla was isolated a series of triterpene fatty acid esters with the carbon numbers 16–21 and 23–29 in the fatty acid part. Oleanolic acid and 3α-hydroxy-lup-20(29)-ene-23,28-dioic acid were also identified.     

Additive Induction of Egr-1 (zif/268) mRNA Expression in Neuroblastoma × Glioma Hybrid NG108-15 Cells via Cholinergic Muscarinic, α2-Adrenergic, and Bradykinin Receptors

Abstract: Administration of carbachol, noradrenaline, and bradykinin induced Egr-1 mRNA expression within 1 h in mouse neuroblastoma × rat gliomahybrid NG108–15 cells. With specific receptor antagonists, the Egr-1 inductions by carbachol and noradrenaline were shown to be mediated via cholinergic muscarinic and α₂-adrenergic receptors, respectively. At their saturation levels for Egr-1 induction, the two agonists had additive effects when added together, but no prolongation of the effect on Egr-1 induction was observed. Addition of carbachol or noradrenaline 6 h after primary stimulation with carbachol or noradrenaline did not result in secondary Egr-1 induction, probably because of receptor desensitization. On the other hand, bradykinin consistently had an additive effect on Egr-1 induction, irrespective of the time of its addition, suggesting that the signal pathways for Egr-1 induction by carbachol or noradrenaline and by bradykinin are different. Treatment of cells with pertussis toxin or cholera toxin strongly inhibited Egr-1 induction by carbachol or noradrenaline but only partially inhibited the induction by bradykinin. Thus, the signals transduced in NG108–15 cells by different neurotransmitter receptors appear to have different effects on Egr-1 induction, depending on the times of stimulation and the combinations of receptors stimulated.     

The vacuolar localization of a basic peroxidase isoenzyme responsible for the synthesis of α-31,41-anhydrovinblastine in Catharanthus roseus (L.) G. Don Leaves

Partially purified protein extracts of Catharanthus roseus leaves were able to couple catharanthine and vindoline to produce α-3′,4′-anhydrovinblastine (AVLB) in a reaction strictly dependent on H₂O₂. This result, and the co-purification of peroxidase with AVLB synthetase activity, strongly suggest a peroxidase-like nature for the coupling enzyme. Only one peroxidase isoenzyme was detected in C. roseus leaves, and it was shown that this isoenzyme consists of a molecularly-heterogeneous basic peroxidase (EC 1-11-1-7) mainly located in the vacuole. These results suggest that a basic peroxidase located in the vacuole may be the main enzyme responsible for AVLB synthesis in C. roseus leaves. This isoenzyme was also found in cell walls where a peroxidase inhibitor was detected.